Apparatus for producing directive forces by induction in alternating current circuits.



Patented Oct. 19, 1915.

2 SHEETS-SHEET I.

//VVE/V TOR:

H. ABRAHAM.

COLUMBIA PLANDGRAPH 1.0 wmurmx n 1 APPLICATION FILED FEB. 24. I912.

- APPARATUS FOR PRODUCING DIRECTIVE FORCES BY INDUCTION IN ALTERNATINGCURRENT CIRCUITS.

W/T/VL'SSES H. ABRAHAM. .7

APPARATUS FOR PRODUCING DIRECTIVE FORCES BY INDUCTION IN ALTERNATINGCURRENT CIRCUITS.

APPLICATION FILED FEB. 24. I912. I 1,157,281. Patented 001.19,1915.

2 SHEETS-SHEET 2.

WITNESSES W jyAZWH/QUJ rrE s a nu HENRI BRAHAM, or PARIS, FRANCE,ASSIGNOR To YIiE BI'ABRAHAM ET JULEs' CARPENTIEB, or PARIS, E 'ANcE. I

APPARATUS FOR PRODUCING DIRECTIVE FORCES BY INDUCTION 1N ALTERNATVING-CURRENT CIRCUITS.

Producing Directive Forces by Induction in Alternating-Current Circuits,of which the followingis a specification. .gThe present inventionrelates to lmprovements in electrical'apparatus, and aims to provideimprovements therein.

- ;In the present invention directlve forces are produced, by means ofinduction, in an alternating current apparatus comprising an'electrornagnet and a coil movable inthe field of the electromagnet,both the electromagnet and coil being suppliedwith alternating current.

The directive forces may be utilized in various ways, as for themeasurement of resistance, for the measurement of frequency, etc.

Figures 1 and 2 show an elevation and a vertical section of theapparatus embodying the invention. Figs. 3 to 6 inclusive illustrateexamples of the application of the present invention to the measurementof various electrical constants.

The same reference numerals are used for similar parts in all thefigures.

Referring to Figs. 1 and 2, the apparatus comprises an inductor 1constituted by superposed rectangular shaped pieces of iron. These ironpieces terminate in two pole pieces Z2 and'carry the exciti'ngcoils a1,fed by alternating current and between which is a'movable'coil. 2mounted on two pivots 0 upon a bracket cl, upon which bracket is fixed acircular core which leaves between its surfac'e'and those of thecylindrically' recessed pole piecespan annular air space in 'whichthecoil 2 canbe moved. The latter bears, through the intermediary of an arm6,

"an indicating hand f. An alternating cur.-

rent -of'the1 same frequency as the current which traverses the coils aisintroduced into the movable coi1 2by'mea'ns of sheets of foil 9. Asshown in these figures, the movable coil 2 is acted uponinductivelybythe alternating field of the electromagnet 1: The coil is includedin'acircuit-containing a capacity B and a self induction 4; If thereactance due to the'capacity 3.1was greater than the reac tance due tothe inductance', the in- Specificatio'n of Letters Patent. PgttefitedGet. 19, 11915; Application filed February 24, 1912. Serial No. 679,554.V

duced' current would lead the electro-motive force and the directiveforce would be negative; it would then be able to counteract thedirective force of an elastic spring. If on the other hand the reactancedue to the inductan-ce was greater than that due to the capacity, thecurrent would lag behind the electro--,motive force; the directive forcewould be positive and would act with or completely replace such aspring. i

In Fig. 3 there is shown a diagram of connections for the case in whichthe apparatus is to serve as an ohm meter. To the binding posts 5 areattached [the conductors ofrthe circuit feeding the electro-magnet 1. Inthe field of the magnet is located the movable coil 2, the two ends ofwhich are attached equilibrium is established in the lVheatstone' bridgeand the coil 2 is traversed by no current, the coil remains in such asymmetrical position that the indicator stands in the mi d-' die of thescale and the current in the coil induced by the electro-magnet equalszero.

This position is a position of stable equilibrium, for if the coil 2 isturned out of this position then the induced current which rises in thecircuit formed by the coil 2 and the in,- duction coil strives to bringthe coil 2 back into the zero position exactly as a spring would do. Ifit is now assumed that one of the resistances of the bridge, for example9, changes, (consequently disturbing the equilibrium of the bridge) thenthe coil 2 re ceives current from the outside and is turned in one orthe other direction according to the displacement of phase which thecurrent in the coil has-as regards the magnetic field. Since, however,the ;induced current. increases in proportion" to the deviation it'Tgives rise to an increasing counter force -which lnnlts the deviatlonand brings the 'coilto rest in a. position of equilibrium,

the-deviation serves as'a measure of the variation of the resistance 9in the bridge.

. 'The operation of the-inductioncoil 4. was

,1 follows :Let the efiective intensity of the magnetic alternatingfield be designated by H, the area of the movable coil by S and the Vangle through which this coil has been re 5 moved from a position forwhich the mag netic flux traversing the coil would be" zero, byte."Furthermore, let the resistance be designated by R, the totalself-induction of the circuit of the coil 2 by L, and the numj her ofalternations of the current by (1).

Then the electro-motive force E induced by the magnetic fieldin the coilhas the value f ll=sin a'si-iw 1'5 and the current strengthis then Vslit: J

This currenttraversing the movable coil ha'sthe value 1 places thedirective force 'ofr springsand M cos g0 wherein the phase differencebetween the magnetic field and the current induced in the coil isdesignated'by P, and wherein this difierence of phase is definedby theformulacol. 1 a I cot Y I now I andcos (flare placedby their .valuesthen there is found for the moment the value rotation movement Mdepends: upon 'the value of the self-induction L in the circuit of themovable coils and is onlystable-when' L is present. IfL was flzero,'thecoil-2 would be inequilibrium' in anyposition Whatever,

I and instead of the self-induction L there were present a condenser,then the 'condi tion of equilibrium in question wou'ld be changed to oneof unstable equilibrium; By

the springs, can be controlledat'willa r r In Fig. 4' there is shownadiagram of an ratus'is to serve as a"frequencymeter. In thiscase, foranfluencmg the d rectionof rotation ofthe coil through a change in the,number of alternations, there'are used two] "supplementing and opposingelectro-motive produces a moment of rotation M, that re- 5 of rotation Mto which the coil is subjectedvariation of the self-induction L, consefquently the returnrotation, movement which" takes: the 'place of thedirective forcel'of;

arrangement for the case in which the appa- 7 forces t One oftheseelectro-motive forces is 7 obtained by a shunt connection with the lowres stance 6, (wh1ch'ilow resistance 6 is con- [nected in serieswith'the electro-magnet 1),

while the second electro-motive force is 0b 7 tained in the'secondarywinding of'a transformer-'8 with an open magnetic 'circuit, 7, whose prmary winding is connected in series with a high non-inductive resistance7. v It iseasilyseen that under these conditions the two electro-motiveforces aredisplaced inphaseby approximately with reference to thepotential of'the system of Wires and can be so connected that they aredirected against each other.- Moreover, one ofthe so electro-motiveforces decreases with the number of alternations; the otherelectromotive force, ontheother hand, increases" In this case,-ontheonehand, that -electro-' motive forcew'hich is derived from the low35 resistance 6 is in phase with the magnetic flux which is displaced by90 as regards the" potential of'the system ofwiresbecause V .t inthe'circuitcontaining the electro magnet' 1 and theresistance 6 thes'elfiinductionis go the overpoweringlforce. V On'the otherliand, 5 theelectr c-motive .force in the. secondary current of thetransformerj 8 is;displaced"by Y 90 as regards the'primary current of this transformer.phase with the currentin the system of It "wires because thenon-inductive resistance 7 This current is, however, in

which is connected in series withlthe primary coil is the overpoweringvfactor. In the arrangement in question the binding 7 posts of the networko fwires are designated 1 g by '5 andthe movable coil by -2,'and 4designates a'self-induction.which-serves for the purpose of controllingthe: counter. force-Q couple and therebyz'the, sensitivenessoft-the 1c5instrument; The electro motive force at; the T L iterminals of theresistance 6 decreases if themagnetic flux, to ;Wl1 l(ll it is:proportional," decreases, as soon-as the frequency increases.

In contradistinction thereto,1t heelectrormo-rlllo I tive force in thesecondary co l of thetrans- '1 former'increa ses, becausethe primary current of this transformer, and-its magnetic induction, attain a valuepractically con stant, whichovalue is'cont rolled by means of resistance7,:1whi-le 'the secondary electro-i motive force increasesproportionalto the "frequency; If now it is assumed that under} definite number ofalternations thejtwo v r I supplementing electro-niotivie forcesmutu-7120 5 ally maintain equilibrium, then the coil 2 -remains its "zero.position and; on account I of the presence of th gselfnducu nc011 4;,

which is GOllnected: inserieswith rthe sec 1' V "ondary 5 windingbfthe'transformer, 18," there [12 5 is produced theforce-rcouplebringing aboutg I stable equilibrium a and; this :force c'ouple takes the place of thespring used: in former devices; If the number-of alternations in- -creases,;-the electrofmotive 'force which is'130 V direction.

derived from the low resistance 6 in the short circuit diminishes, butthe "electromotive force in'the secondary winding of the transformer 8increases, and the resulting current turns the coil in a definitealternations would have brought about devi-' ation in the reversedirection. However, the

counter induction force-couple also increases here in proportion to thedeviation and finally this force-couple brings the coil to rest in aposition of equilibrium.

7 Fig. shows by way of example an embodiment which is based upon thesameprinciple. 'The condenser 3 is connected in parallel with theelectro-magnet l, and the resulting current moves the coil 2 with whicha self-induction is connected in parallel and this controls the opposingforce couple. The condenser?) plays a role Which is equiv- .alent tothatof the transformer 8 of Fig. 2.

It produces in the coil a current component which increases if thefrequency increases,

'while the componentarising from the magnetic flux diminishes if thefrequency increases. According to the overbalancing of the one or theother of the two current (301111 ponents, which are relatively displacedin 3 phase by 180, the coil is deviated either to the right or to theleft from the zero point.

In Fig. 6 there is illustrated the connec:

tion of two similar devices which are fed by an alternating currentunder a constant frequency. It is in this manner possible to obtain arelay system which has the quality that on the displacing of one of thecoils by an external force, for example by hand, the other coil is alsodeviated by the induction current created. In this device 14 and 16designate the electro-Inagnets of the two apparatuses, 2 and 13 themovable coils, 3 a condenser, 15 a non-inductive resistance and aself-induction. If the coil 2 is deviated from'its position there arisestherein an induction current which traverses the coil 13 and deviatesthis. In consequence of the deviation of the coil'13 there also arisestherein an induction current which fiows through 13, 4, '15, and inconsequence A decrease in the number of of the presence of theself-induction 4:, as was previously explained, produces a counterrotation moment so that the coil 13 assumes a definite position ofequilibrium. It is stillto be mentioned that the condenser 3 of Fig.Ghas forits object the offsetting of the self-induction of the currentof the coil 2 and thus to suppress the directive force of the inductionin this coil in such a manner that it can take place without thereaction of the external electro-motive force. The object of theself-induction coil 1 is to impart to the coil of the receivingapparatus a noticeable directive force and the resistance 15 allows ofmaking to a noticeable extent the circuits of the two coils independentand to avoid reaction of the receiving coil upon the sending coil. I'hecoil 2 is consequently entirely free, because its movement gives nooccasion for the arising of any counter force pair, and because,moreover, the coil 13 in its deviation exercises no reaction upon thecoil 2. On the other hand the coil 13 is moved along by the coil 2 ifthis is displaced by any external cause.

librium, without the intervention of mechan-.

ical force, in accordance with the electrical conditions of the circuitas regards resistances and reactances, but independent of the potential.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

HENRI ABRAHAM.

\Vitnesses LUOIEN MEMMINGER, GABRIEL BELLIARD.

i Copies of this patent may be obtainedfor five cents each, byaddressing the Commissioner of Patents,

1 Washington, D. C.

